I. Field of the Invention
The invention relates to wireless communications. More particularly, the invention relates to interfacing a wireless signal with an FM receiver.
II. Description of Related Art
Electronic equipment may include numerous output capabilities from which a user may select. For example, electronic equipment may provide visual output via a display, audio output via a speaker, wireless output, or some combination thereof. The electronic equipment may provide wireless output by modulating the visual output onto a television carrier or modulating audio output onto a radio carrier, such as a Frequency Modulation (FM) radio carrier.
Typically, the electronic equipment does not monitor the output RF band, but relies on a user to select the desired output band from a set of fixed choices. For example, electronic equipment may permit RF video output on one of NTSC television channels 3 or 4. A user can configure the electronic device for the desired television, and can tune a local television to the corresponding channel to receive the modulated video signal.
Similarly, the electronic equipment may permit RF audio output on one or two predetermined FM channels. The user can select the desired FM channel and the electronic equipment can modulate the audio signal onto the carrier of the selected FM channel. The user can tune a local radio receiver to the corresponding frequency to receive the modulated audio.
However, existing broadcasters may already be using the desired output band. In the case of NTSC video, existing local broadcasters may already be broadcasting on either or both of channels 2 and 3. Similarly, existing local FM radio broadcasters may already be broadcasting on the fixed selection of radio output frequencies. Existing broadcasters appear to the electronic equipment as interference sources, and their presence may significantly degrade the signal quality from the electronic device. The user may not have the ability to successfully configure an RF modulated output signal from the electronic device in situations where the existing broadcasters occupy the spectrum for all of the fixed RF output selections.
Incorporating RF output capabilities in a portable electronic device poses additional issues. The mobility of a portable electronic device further complicates the operating environment and increases the probability that a broadcaster will transmit interfering signals over the selected RF output frequency. The portable electronic device may initially be outside of a broadcast area but may move into a broadcast area. Thus, a selected RF output frequency may initially provide a sufficient signal quality, but the signal quality may degrade to unacceptable levels as the portable electronic device moves into an area having a broadcaster on the selected RF output frequency.